1. Field of the Invention
The present invention relates to illuminated signs such as backlighted signs having an information or visual content bearing front panel with translucent and/or transparent portions through which backlighting may be perceived. The present invention relates to configurations and layouts of backlighting elements for such signs.
2. Description of the Related Art
Generally a sign or advertisement board may be formed by printing characters and/or images or attaching printed material on the surface of a metallic plate or a synthetic resin plate. However, such advertisement boards have low visual recognition in daytime and worse visual recognition at night and in snowy, rainy and foggy weather conditions, such that an observer, such as a vehicle driver or passenger, cannot easily recognize the sign's information content.
With reference to FIGS. 1A and 1B, a conventional backlighted illuminated advertisement board 40 may have one or more light guide plates 10 and light emitting diode (LED) units 20 installed behind a sign panel 50. LED units 20 are affixed to direct light into the edge of an adjacent light guide plate 10 which redirects the light into its surface and sign panel 50 so that the light may be transmitted through transparent or translucent portions of sign panel 50 and observed by an observer. In this way, visibility and recognition of information content of board 40 is possible in bad weather and at night.
However, such conventional boards suffer from uneven illumination in which light does not reach central portions, especially with larger advertisement boards. For example, area 55 of sign panel 50, not positioned directly above a light guide plate, may not receive the same amount of backlighting as the remainder of sign panel 50. Observers are unable to recognize the visual content of such portions of conventional advertisement boards. Such conventional signs may also have a visible dark seam corresponding to the location of adjacent light guide plates. Moreover, the conventional board is not constructed for ease of replacement of LED units.